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In this clinical trial, a research team of three foreign-trained osteopaths affiliated with the German Academy of Osteopathy and the European College of Osteopathy studied the application of osteopathic manipulation for chronic nonspecific neck pain. The quality of this controlled clinical trial compares favorably with a similar trial conducted in Spain (Man Ther. 2009;14:306-313), as reviewed on page 475.

German researchers recruited 41 subjects from the Munich-metropolitan area. All subjects had a history of chronic nonspecific neck pain lasting at least 3 months. All subjects also showed osteopathic dysfunction in four or more of the seven areas of the cervical spine studied and reported a pain level of 4 or higher on a 10-point subjective pain scale. Exclusion criteria included manipulative treatment in the past 3 months, circulatory disorders of the vertebral artery, and late whiplash syndrome.

Subjects were randomly assigned to either an intervention (n=23) or control group (n=18). They were required to complete a medication questionnaire and diary throughout the investigation. Physicians examined all subjects and took radiographic images of each subject's spine. Primary outcome measure was self-reported pain level. Secondary outcome measures were the results of the Northwick Park Pain Questionnaire and the validated German Medical Outcomes Study 36-Item Short Form (SF-36) questionnaire.

All interventions were provided by the investigators, three foreign-trained osteopaths working in Germany as physiotherapists or “heilpraktiker” (ie, natural health professionals). Every 4 to 10 days, subjects from both study groups underwent a 45-minute treatment session consisting of an osteopathic structural assessment (∼30 min) and a sham therapeutic ultrasound (∼2 min). The intervention group also received 30 minutes of osteopathic manipulation during every other session (ie, every 12 to 20 d). Direct (high-velocity, muscle energy, myofascial release), indirect (functional techniques, balanced ligamentous tension), visceral, and cranial techniques were used for the intervention group. A manual sham protocol was not developed by researchers for this investigation. The study protocol was composed of a total of nine such sessions and two posttreatment follow-up interviews.

Subjects completed pain scales at each visit and sent a final questionnaire via mail to the therapists 1 week after the last treatment session. In addition, researchers followed up with all 40 subjects via telephone 3 months postintervention.

One subject in the intervention group dropped out of the study for unknown reasons. Two subjects from the control group withdrew from the study because of aggravated pain.

There were no statistically significant differences in the demographic characteristics of the study groups.

Using the subjective pain scale, the experimental group reported steadily decreasing pain levels at all nine visits with further pain reductions reported at 3-month follow-up. The pain scale allowed subjects to report actual pain intensity at the time of the clinic visit, as well as average and worst pain intensity within the 1-week period leading up to each visit. Differences in actual and worst pain intensity between the two groups approached, but did not reach, statistical significance for each of the nine treatment visits and 1-week posttreatment follow-up. However, for this same period, differences in average pain intensity for the week leading up to each visit was statistically significant (P<.017).

When follow-up data from the 3-month posttreatment telephone interview were factored in, pain ratings for the intervention group were notably lower than those of the control group for actual (P<.031) and average pain intensity (P<.009). During the nine treatment visits and 1-week posttreatment follow-up, average pain intensity decreased by 2.5 points for the intervention group, but only 0.7 points for the control group (P=.017; 95% CI, –3.13 to –0.32). When data from 3-month follow-up were included, the average pain intensity decreased by 2.8 points for the intervention group and only 1 point for the control group (P=.009; 95% CI, –3.07 to –0.48).

Secondary outcomes from the Northwick Park Pain Questionnaire showed reductions in pain for the intervention group, with P=.045 posttreatment and P=.011 at 1-week follow-up.

The study's authors acknowledged that the additional time taken for osteopathic manipulation during every other intervention group visit may have had an effect on study outcomes. However, given the magnitude of the differences, they speculated that the effect was negligible. The authors also surmised that the continued reduction in pain reported by the intervention group at 3-month follow-up may be related to the osteopathic principle of stimulating the body's natural ability to heal.

Of particular interest to osteopathic medical researchers is the nature of the treatment protocol. The protocol for this German study was a “treat what you find with what works best” approach, which is the traditional approach in clinical practice for osteopathic physicians. From the research design perspective, the combination, number, and sequence of techniques used probably could not be duplicated in another study—even if conducted by the same osteopaths—because of subject variability. The authors justify this protocol on the basis that it represents what takes place in actual practice. From a scientific standpoint, the justification of this protocol is debatable. However, it does typify a major concern for future research in manual medicine.

Under consideration at the present time by a consortium of osteopathic researchers including The Osteopathic Research Center and A.T. Still Research Institute are plans for a large-scale observational study, similar to the Framingham Study (JAMA. 1989;262:41-44), in that it would be longitudinal and cover primary care delivered by all physicians, DOs—many of whom would ostensibly use osteopathic manipulative treatment—and MDs. If the proposed study is conducted, the osteopathic manipulative treatment used would not be a specific set of techniques or a set protocol, but would resemble the design used in this German study. —HHK

Schwerla F et al. Forsch Komplementmed. 2008;15:138-145.

Spinal Thoracic Thrust Manipulation Reduces Neck Pain

Thoracic spine thrust technique was the primary experimental intervention used in this clinical trial conducted by researchers at the Escuela de Osteopatia de Madrid in Spain. Thoracic spine thrust manipulation—the only manual procedure used in this study—is identical to an osteopathic manipulative treatment technique for the mid-to-upper thoracic spine called the “reverse osteopathic hug.” The article features an illustration from Manipulation of the Spine, Thorax and Pelvis: An Osteopathic Perspective (Churchill Livingstone, 2005), but the technique depicted is virtually identical to that practiced by many osteopathic physicians and appears in An Illustrated Practice of Osteopathy - 1908 (The Still National Osteopathic Museum, 2005).

In this trial, 45 participants (20 men and 25 women) were randomly assigned to either the control or experimental group. All participants had acute neck pain and were referred by primary care physicians to a physical therapy clinic. Exclusion criteria included history of whiplash and spinal manipulative therapy in the previous 2 months.

Both groups received six sessions (two sessions per week for 3 weeks) of standard electrotherapy (transcutaneous electrical nerve stimulation applied for 20 min at C7 vertebra), superficial thermal therapy (an infrared lamp applied 50 cm from the subject's neck for 15 min), and soft tissue massage. In addition, those in the experimental group received thoracic thrust manipulation once per week.

There were three outcome measures. Data were collected at the first clinic visit (baseline) and 1 week after the final clinic visit. Neck pain was reported by subjects using a subjective 11-point pain rating scale. In addition, the effect of neck pain on activities of daily living was determined using the Northwick Park Neck Pain Questionnaire. Cervical range of motion was assessed with a cervical goniometer.

All participants completed the trial; intention-to-treat analyses were applied for missed visits. While both control and experimental participants showed improvement on all three outcome measures, subjects receiving thoracic manipulation showed statistically significant greater improvement. Two-way repeated-measures analysis of variance showed statistical significance for pain intensity (P<.001) and disability (P<.001). There was a 2.3-point reduction in reported pain from baseline to 1-week posttrial for participants receiving thoracic manipulation. The active cervical range-of-motion assessment showed improvement in all planes of motion for those receiving thoracic manipulation. Between-group differences were 10.6 degrees for flexion; 9.9 degrees for extension; 9.5 degrees and 8 degrees for right and left lateralflexion, respectively; and 9.6 degrees and 8.4 degrees for right and left rotation, respectively.

The significant effect of this singularly simple intervention is compelling given the modest sample size. The manipulation procedure was applied in a very short duration of time—though not specified in the article, the literature cited as the precedent for this study described the procedure taking 15 to 45 seconds from start to finish (Cleland et al. Man Ther. 2005;10:127-135). This short period allocated for the manual procedure mediated against the possible criticism that statistically significant differences were observed in the experimental group data only because those participants received a longer intervention.

The major shortcomings of the study were its short, 5-week duration and single-site recruitment of subjects. Since follow-up was 1 week after the final treatment visit, it is unknown how long the positive changes lasted. In addition, the ability to generalize would have been stronger with a multicenter design. The authors also acknowledged that other thoracic manipulation procedures may be more efficacious and suggest further study.

The authors could only speculate about the possible mechanism of action for thoracic manipulation. It is unknown whether the effect was segmental or central—or whether a reduction in muscle spasm or increased intersegmental joint play mediated the improvements observed. The close proximity of mid-to-upper thoracic structures to cervical structures and direct connections via ligaments (eg, interspinous) and muscles (eg, trapezius) suggest both biomechanic and neurologic possibilities—consistent with the osteopathic principle that structure and function are interrelated.

While practice guidelines for treating chronic low back pain include spinal manipulation, additional research is needed on the safety and efficacy of this treatment modality, especially on the possibility of vertebral artery compromise. This Spanish clinical trial adds to the growing body of evidence supporting the use of spinal manipulation for the treatment of neck pain. —HHK

Gonzáles-Iglesias J et al. Man Ther. 2009;14:306-313.

Effects of Stretch-Activated Mechanotransduction on Nerve Terminals

While pharmacologic-related research has dominated basic science research on nerve stimulation and function, the effects of mechanical impact on nerve function (mechanotransduction) is receiving increased attention. In fact, a recent study conducted by researchers at the Institute of Biomedical Sciences (Taipei, Taiwan) and at Carnegie Mellon University (Pittsburgh, Pa) used in vitro methods to evaluate mechanical stretch effects on neuromusculoskeletal structures. This study focused on the effect of stretch-activated mechanotransduction on nerve terminal action potentials.

The researchers cultured dorsal root ganglion neurons harvested from CD1 strain mice on a polydimethylsiloxane (PDMS) elastomeric substrate. The cells were seeded on a PDMS layer on the top of a coverslip and coated with either fibronectin or poly-L-lysine, creating an extracellular matrix (ECM). Whole-cell patch recordings of the dorsal root ganglion neurons were made with patch pipettes. Mechanical force was applied to the PDMS by a flame-polished pipette with a tip diameter of approximately 4 μm. The indentation pipette, positioned 100 μm away from the main cell body of the recorded neuron, imposed a displacement on the PDMS, avoiding glia cells. A micromanipulator was used to control indentation.

Displacement was applied in increments of 10.43 μm until an action potential (AP) response occurred or displacement reached a maximum of 125 μm. When an indentation produced an AP, the same indentation was applied again to see whether the stretch-activated AP was repeatable; it was repeatable virtually 100% of the time. Displacement lasted less than 1 second, with a minimum of 30 seconds between indentations.

Resting membrane potentials were notably different in the resting state compared to indented PDMS. Neurons coated with fibronectin exhibited lower thresholds of activated APs when compared to neurons cultured in poly-L-lysine coating. The authors indicated these results imply that cell-ECM interactions are important in neural mechanotransduction, corroborating previous findings that mechanotransductive response is determined by the cytoskeletal structure.

For both cell-coating types, AP responses significantly increased the closer the indentation was to the cell body (range, 30-100 μm). Action potentials were blocked by channel blockers, in this case cytochalasin-D and latrunculin-A, nocodazole. Blockage was caused by the depolymerization of the cytoskeleton—not the inhibition of voltage-dependent ion channels. None of the cytoskeleton-modification agents altered the resting membrane potential of the neurons. The magnitude to the AP response depended on the size of the cell (27-33 μm), the amount of stretch induced (8%-35%), and indentation depth (50-100 μm).

The authors concluded that neural AP firing through nerve terminal is linked to specific mechanical deformations and ECM interactions. These findings have implications in the field of manual medicine and therapy. The enhancement of lymph flow by lymphatic pump techniques was assumed for decades before being demonstrated in canine subjects by Knott et al (J Am Osteopath Assoc. 2005;105:447-456). The impact of osteopathic manipulative treatment (OMT) at the cellular level is elucidated by studies such as this one, which will help answer research questions on the kind of cells affected by OMT and whether normal, injured, or diseased cells react differently to OMT. Likewise, further research is needed regarding the delivery of OMT forces and the direction of force in relation to the cell.

Mechanotransduction research may also have implications for studies investigating biomarkers related to OMT—including β-endorphin (J Am Osteopath Assoc. 2007;107:387-400) and endocannabinoids (J Am Osteopath Assoc. 2005;105:283-291)—in that different OMT techniques with very different biomechanic characteristics may produce different effects. If nothing else, this particular article exemplifies the growing interest in mechanotransduction. This biomechanic perspective is consistent with the admonition of osteopathic medicine's founder Andrew Taylor Still, DO, MD, to attend to “anatomy, anatomy, anatomy” in the delivery of healthcare—an idea long overshadowed by reliance on pharmacologic agents. —HHK

Lin YW et al. PloS One [serial online]. 2009;4:e4293 .

“The Somatic Connection” highlights and summarizes important contributions to the growing body of literature on the musculoskeletal system's role in health and disease. This section of JAOA—The Journal of the American Osteopathic Association strives to chronicle the significant increase in published research on manipulative methods and treatments in the United States and the renewed interest in manual medicine internationally, especially in Europe.